(USA TODAY) SALEM, Ore. -- Very low levels of radiation from the Fukushima nuclear disaster likely will reach ocean waters along the U.S. West Coast next month, scientists are reporting.
Current models predict that the radiation will be at extremely low levels that won't harm humans or the environment, said Ken Buesseler, a chemical oceanographer at the Woods Hole Oceanographic Institution who presented research on the issue last week.
But Buesseler and other scientists are calling for more monitoring. No federal agency currently samples Pacific Coast seawater for radiation, he said.
"I'm not trying to be alarmist," Buesseler said. "We can make predictions, we can do models. But unless you have results, how will we know it's safe?"
The news comes three years after the devastating Japan tsunami and resulting nuclear accident.
On March 11, 2011, a 9.0 magnitude earthquake hit off the coast of Japan, triggering a tsunami with waves as high as 133 feet. More than 15,000 people died and about 6,000 were injured.
The earthquake and tsunami knocked out power to cooling pumps at the Fukushima Daiichi nuclear power plant complex, causing meltdowns at three reactors.
Last July, Tokyo Electric Power Co., which operates the plant, acknowledged for the first time that the reactor was leaking contaminated underground water into the ocean.
Since then, the news has gotten worse, and there is widespread suspicion that the problem is underreported.
There are three competing models of the Fukushima radiation plume, differing in amount and timing. But all predict that the plume will reach the West Coast this summer, and the most commonly cited one estimates an April arrival, Buesseler said.
A report presented last week at a conference of the American Geophysical Union's Ocean Sciences Section showed that some Cesium 134 has already has arrived in Canada, in the Gulf of Alaska area.
Cesium 134 serves as a fingerprint for Fukushima, Buesseler said.
"The models show it will reach north of Seattle first, then move down the coast," Buesseler said.
By the time it gets here, the material will be so diluted as to be almost negligible, the models predict. Radiation also decays. Cesium 134, for example, has a half-life of two years, meaning it will have half its original intensity after that period.
In Oregon, state park rangers take quarterly samples of surf water and sand at three locations along the coast. The water is analyzed for Cesium 137 and iodine 131. Both of those already exist in the ocean at low levels from nuclear testing decades ago.